Final answer:
Among the options provided, ribosomes are the example of nonmembrane organelles. Mitochondria, the Golgi apparatus, and the nucleus are membrane-bound organelles. The endomembrane system is crucial for protein synthesis and transport, and evidence supporting the endosymbiotic theory for mitochondria includes their bacterial-like DNA and ribosomes.
Step-by-step explanation:
An example of a nonmembrane organelle among the options is ribosomes. Unlike ribosomes, mitochondria, the Golgi apparatus, and the nucleus are all enclosed by membranes, making them membrane-bound organelles. Ribosomes are not enclosed within a membrane but are still considered organelles due to their specific cellular functions. Mitochondria are referred to as the power plants of the cell because they perform cellular respiration and produce ATP, which is the cell's main energy currency. The endomembrane system involves the endoplasmic reticulum, the Golgi apparatus, and vesicles, working together to produce, package, and export cellular products, including proteins.
The nucleus, ribosomes, rough endoplasmic reticulum, and Golgi apparatus work together to synthesize and transport proteins within the cell. The DNA in the nucleus provides the instructions for protein synthesis, which occurs in ribosomes found in the cytoplasm or on the rough endoplasmic reticulum (ER). The rough ER assists in the folding and processing of proteins, which are then transported to the Golgi apparatus for further modification and sorting for transport to their final destinations. Vesicles and vacuoles play key roles in storage and transport within the cell, and all cells require ribosomes for protein synthesis, including prokaryotic cells that lack a true nucleus and other cell organelles.